Abstract:

A combustion furnace includes a blower housing with a centrifugal blower
impeller disposed therein and plural heat exchanger tubes disposed
substantially around a major portion of the periphery of the impeller.
The heat exchanger tubes receive combustion gasses from plural burner
nozzles and discharge combustion gasses to a plenum in communication with
a motor driven inducer gas pump. The integrated blower housing and heat
exchanger may be disposed in a cabinet including support structure for a
fuel delivery manifold, associated burner nozzles and forming air inlet
and outlet openings for air being circulated by the blower.

Claims:

1. A heater for circulating heated air to an enclosed space, said heater
comprising:a blower housing including an outer wall and opposed
sidewalls;a rotatable impeller disposed within said blower housing for
circulating air through said blower housing between at least one air
inlet opening and at least one air discharge opening in said blower
housing; andplural heat exchange conduits disposed within said blower
housing and disposed wound at least a portion of the periphery of said
impeller for heating air circulated by said impeller within said blower
housing, wherein at least one heat exchange conduit of the plural heat
exchange conduits comprises a heat exchange tube with a major portion
having a generally cylindrical cross section.

2. The heater set forth in claim 1 including:a motor mounted on said
blower housing and drivingly connected to said impeller.

3. The heater set forth in claim 2 wherein:said blower housing includes
opposed air inlet openings formed in respective ones of said sidewalls.

4. The heater set forth in claim 3 wherein:said sidewalls are tapered
axially with respect to an axis of rotation of said impeller and at least
partially around said periphery of said impeller.

5. The beater set forth in claim 4 wherein:said impeller comprises a
centrifugal impeller directly connected to said motor.

7. The heater set forth in claim 6 wherein:said heat exchange tubes
include gas inlet ends projecting through said outer wall of said blower
housing, respectively.

8. The heater set forth in claim 6 wherein:said burner nozzles are
arranged side by side adjacent a fuel manifold for receiving combustion
fluid fuel for combustion in said burner nozzles whereby combustion
gasses generated in said burner nozzles are transported through said heat
exchange tubes.

9. The heater set forth in claim 6 wherein:said heat exchange tubes have
plural sections disposed such that said air circulating within said
blower housing contacts successive ones of said sections during flow from
said impeller to said at least one discharge opening.

10. The heater set forth in claim 9 wherein:selected ones of said sections
are disposed closer to said impeller than others of said sections.

11. The heater set forth in claim 6 wherein:said heat exchange tubes
include respective discharge ends opening into a plenum of said heater
for discharging combustion gasses thereto.

12. The heater set forth in claim 11 including:a combustion gas flow
inducing blower operably connected to said plenum for inducing flow of
combustion gasses through said heat exchange tubes and for discharge to a
flue conduit.

13. The heater set forth in claim 6 including:a cabinet supporting said
blower housing including a first wall having an opening in communication
with said at least one discharge opening in said blower housing, and
spaced apart sidewalls connected to said first wall and forming a space
for directing airflow to said at least one inlet opening in said blower
housing.

14. The heater set forth in claim 13 including:a support wall part
including plural openings formed therein aligned with gas inlet ends of
said heat exchange tubes and for receiving combustion gasses from
respective ones of said burner nozzles.

15. The heater set forth in claim 6 wherein:said heat exchange tubes each
include a first section directly in communication wit one of said burner
nozzles, said first section being substantially linear, plural curved
sections configured for orienting said heat exchanger tube about the
periphery of said impeller and a discharge section in communication with
a plenum.

16. The heater set forth in claim 15 wherein:a major portion of each of
said heat exchanger tubes has a generally cylindrical cross section and
said discharge section has a substantially elliptical cross section.

17. A heater for circulating heated air to an enclosed space, said heater
comprising:a blower housing including an outer wall and opposed
sidewalls;a centrifugal impeller disposed within said blower housing for
circulating air through said blower housing between at least one air
inlet opening and at least one air discharge opening in said blower
housing;a motor mounted on said blower housing and drivingly connected to
said impeller; andplural side-by-side heat exchange tubes disposed within
said blower housing and disposed around at least a major portion of the
periphery of said impeller for heating air circulated by said impeller
within said blower housing, wherein a major portion of at least one heat
exchange tube of the plural heat exchange tubes has a generally
cylindrical cross section.

18. The heater set forth in claim 17 including:plural burner nozzles
arranged side by side adjacent a fuel manifold for receiving combustion
fluid fuel for combustion in said burner nozzles whereby combustion
gasses generated in said burner nozzles are transported through said heat
exchange tubes.

19. The heater set forth in claim 18 wherein:said heat exchange tubes
include respective discharge ends opening into a plenum of said heater
for discharging combustion gasses thereto.

20. The heater set forth in claim 18 wherein:said heat exchange tubes each
include a first section directly in communication with one of said burner
nozzles, said first section being substantially linear, plural curved
sections configured for orienting said heat exchanger tube about the
periphery of said impeller and a discharge section in communication with
a plenum.

21. The heater set forth in claim 20 wherein:a major portion of each of
said heat exchanger tubes has a generally cylindrical cross section and
said discharge section has a substantially elliptical cross section.

22. The heater set forth in claim 17 including:a cabinet supporting said
blower housing including a first wall having an opening in communication
with said at least one discharge opening in said blower housing, and
spaced apart sidewalls connected to said first wall and forming a space
for directing airflow to said at least one inlet opening in said blower
housing.

23. The heater set forth in claim 17 wherein:said heat exchange tubes have
plural sections disposed such that said air circulating within said
blower housing contacts successive ones of said sections during flow from
said impeller to said at least one discharge opening.

24. The heater set forth in claim 23 wherein:selected ones of said
sections are disposed closer to said impeller than others of said
sections.

Description:

BACKGROUND OF THE INVENTION

[0001]In the development of heating equipment, including combustion
furnaces, particularly for use in heating enclosed spaces, there has been
a continuing need to provide a heater which is compact, economical to
manufacture and energy efficient. Conventional combustion furnace type
heaters, for example, include separate heat exchanger and blower or fan
housing structures which are disposed within a generally rectangular
box-like cabinet having an air inlet opening for so-called return air and
an air outlet opening for so-called supply air. However, the requirements
mentioned above with respect to overall physical size of the heater or
furnace, the cost of manufacture and energy efficiency continue to be
motivating factors for further developments and it is to these ends that
the present invention has been developed.

SUMMARY OF THE INVENTION

[0002]The present invention provides an improved heater for forced air
heating of enclosed spaces wherein a heat exchanger is integrated with a
housing for a motor driven rotating fan or blower. In particular, the
invention is directed to a compact forced air furnace for heating air
deliverable to an enclosed space and wherein a combustion heat exchanger
is integrated into a centrifugal blower housing.

[0003]In accordance with one important aspect of the present invention, an
integrated heat exchanger and blower housing is provided comprising a
compact combustion furnace wherein multiple heat exchanger tubes are
disposed within a generally spiral or scroll-type housing for a
centrifugal blower wheel or impeller. Multiple side-by-side heat
exchanger tubes substantially encircle a centrifugal blower impeller
disposed within a blower housing. In this way a heat exchanger is
provided which is integral with the forced air blower structure and the
blower housing forms an integral part of the heat exchanger as well as
performing a conventional function of directing air to and from a
centrifugal air moving impeller.

[0004]In accordance with another aspect of the present invention, a
compact combustion furnace is provided which includes a blower housing
including an integrated heat exchanger surrounding a centrifugal impeller
or fan which is connected to a motor mounted on the blower housing.
Plural side-by-side heat exchanger tubes are oriented to be in proximity
to spaced apart burner nozzles, preferably mounted outside of the blower
housing. The heat exchanger tubes substantially encircle the centrifugal
blower impeller and are oriented to discharge combustion gasses into a
plenum for evacuation from the furnace, which evacuation may be induced
by a motor driven blower. Plural elongated burner tubes are oriented to
include portions disposed downstream in the direction of air flow being
impelled radially, outwardly and circumferentially with respect to the
rotating centrifugal impeller. The configuration of the heat exchanger
tubes with respect to cross sectional shape may be varied to minimize
resistance to flow of air which is being heated through contact with the
multiple heat exchanger tubes.

[0005]In accordance with yet a further aspect of the present invention, a
forced air combustion furnace is provided which includes a compact,
generally rectangular outer cabinet, a centrifugal blower housing mounted
within the cabinet and a combustion furnace heat exchanger integrated
into and with the blower housing and comprising plural side-by-side heat
exchanger tubes arranged to allow airflow over substantially the entire
surfaces of each tube to provide maximum heat exchange between combustion
gasses flowing within the tubes and air circulating over the exterior
surfaces of the tubes and being impelled by a centrifugal blower.

[0006]Those skilled in the art will further appreciate the above-mentioned
advantages and superior features of the invention together with other
important aspects thereof upon reading the detailed description which
follows in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is perspective view showing a heater comprising a combustion
furnace with an integrated heat exchanger and forced air blower housing
arrangement in accordance with the present invention;

[0008]FIG. 2 is a perspective view of the furnace shown in FIG. 1 and
taken from a different direction;

[0009]FIG. 3 is a top plan view of the furnace shown in FIGS. 1 and 2 with
the outer cabinet removed;

[0010]FIG. 4 is a perspective view of the integrated blower housing and
heat exchanger showing the general arrangement of plural heat exchanger
tubes disposed within a scroll-like combination blower and heat exchanger
housing;

[0011]FIG. 5 is a transverse section view taken generally along the line
5-5 of FIG. 1;

[0012]FIG. 6 is a perspective view of one side of the blower housing; and

[0013]FIG. 7 is a perspective view of an opposite side of the blower
housing.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0014]In the description which follows, like parts are marked throughout
the specification and drawing with the same reference numerals,
respectively. The drawing figures may not be to scale and certain
features may be shown exaggerated in scale or in somewhat generalized or
schematic form in the interest of clarity and conciseness.

[0015]Referring to FIGS. 1 and 2, there is illustrated a heater for
heating air for circulation within an enclosed space and generally
designated by the numeral 10. The heater 10 in accordance with the
invention is advantageously characterized as a combustion furnace and
includes a generally rectangular cabinet 12 having opposed sidewalls 14
and 16, a backwall 18 and a removable front wall 19, a major portion of
which is shown removed in the drawing figures. A relatively large air
inlet opening 20 is defined by the opposed sidewalls 14 and 16, the
backwall 18 and a cabinet frame member 22. A generally planar topwall 24,
FIG. 1, has a suitable opening 26 formed therein for discharging air from
the cabinet 12 for flow to a usage such as an enclosed space, not shown,
within a residential or commercial building, for example. Air returning
from the enclosed space enters the cabinet 12 through the inlet opening
20. Sidewall 14 may include a generally rectangular opening 15 normally
covered by a service cover, not shown, so that by removing the service
cover and blocking opening 20, return air may enter the cabinet interior
space, generally designated by numeral 23, FIG. 2, via opening 15.

[0016]Disposed within the cabinet 12 is a scroll type blower housing,
generally designated by the numeral 28. As shown also in FIGS. 3, 5, 6
and 7, blower housing 28 includes a somewhat scroll or spiral shaped
outer wall 30, opposed tapering sidewalls 32 and 34, see FIGS. 3, 6 and
7, and coaxial inner wall parts 33 and 35, see FIGS. 6 and 7, defining
opposed air inlet openings 36 and 38. An air discharge opening 40 is
defined by outer wall 30, opposed sidewalls 32 and 34 and an inner wall
part 42, which is intersected by the outer wall 30 and is contiguous with
the sidewalls 32 and 34, as shown in FIGS. 3, 6 and 7. Accordingly,
housing 28 defines a flowpath for air being induced into the housing
through openings 36 and 38 and being discharged through opening 40
wherein, preferably, a continuously increasing cross sectional area of
the air flowpath is provided when viewed in circumferentially spaced
radial planes extending from the central axis 39 of the openings 36 and
38. Accordingly, blower housing 28, when mounted within cabinet 12, is
disposed such that its air outlet opening 40 is directly adjacent to
opening 26 in cabinet topwall 24. Sidewalls 32 and 34 of housing 28 are
suitably spaced-from sidewalls 14 and 16 within the interior space 23 of
cabinet 12 to allow unrestricted airflow from opening 20 through the
interior space and into the air inlet openings 36 and 38 of housing 28.

[0017]Referring further to FIGS. 1, 2, 3 and 5, cabinet 12 is provided
with an interior transverse wall 44 having a substantially vertical part
44a, parallel to backwall 18 and a part 44b which slopes toward front
wall 19 of cabinet 12, as shown. Cabinet wall part 44a is contiguous with
a part of outer wall 30, see FIG. 3, and supports a combustion gas
plenum, generally designated by the numeral 50. Plenum 50 supports a
motor driven combustion gas inducer pump or fan 51 including a drive
motor 52, FIGS. 2 and 3, for driving a centrifugal impeller, not shown,
in flow communication with the plenum 50 for discharging combustion
gasses through a discharge conduit 56, FIGS. 1, 2 and 5. An elongated,
generally flat plate support bracket 58, FIGS. 1 and 2, extends between
and is supported by sidewalls 14 and 16, extends generally parallel to
wall part 44b and is spaced therefrom. Plate-like support bracket 58 is
operable to support spaced apart combustion gas burner nozzles 60, six
shown by way of example. Burner nozzles 60 are aligned with combustion
fuel gas discharge nozzles 62, respectively, and which are mounted on a
tubular manifold 64 connected to a conventional fuel flow and pressure
regulator control valve 66, adapted to be connected to a source of fluid
fuel, such as natural gas. Manifold 64 is suitably supported within the
interior of cabinet 12 by opposed brackets 65 and 67, FIGS. 1 and 2.
Burner nozzles 60 are also provided with suitable igniter devices, not
shown in the drawing figures.

[0018]Wall part 44b is provided with plural spaced apart openings 69,
FIGS. 1 and 2, aligned with each of the burner nozzles 60, respectively.
Heated combustion gasses and induced air flow through the openings 69
into respective heat exchanger conduits comprising combustion gas
conducting tubes 70, FIGS. 4 and 5, major portions of which are disposed
side by side, substantially parallel to and spaced apart from each other,
as shown, and within the interior space 71 of blower housing 28. As shown
in FIG. 5, by way of example, each of combustion gas heat exchanger tubes
70 includes an inlet end 73 connected to wall part 44b and aligned with
an opening 69 therein. Tubes 70 each include a substantially straight or
linear section 74, preferably of cylindrical cross section geometry,
extending through outer wall 30 and within space 71 to a first curved
section 76 contiguous with a second linear or straight section 78 which
is contiguous with additional curved sections 80, 82, 84 interconnected
by linear sections 81 and 83. The cross section of each heat exchanger
tube 70 between inlet end 73 and the gas discharge end of curved section
84 may be substantially cylindrical, however, the cross section shape of
the straight or linear tube sections, in particular, may be of different
geometry to improve heat transfer. A generally cylindrical linear
transition piece 86 is connected to a final gas discharge tube section 88
which is preferably of somewhat elliptical cross section, see FIG. 3
also, so as to minimize the projected cross sectional area exposed to
airflow being discharged from blower housing 28 and to provide for
communication with plenum 50. Heat exchanger tube sections 86 project
through a blower cutoff wall section 43 adjacent discharge opening 40, as
illustrated in FIGS. 3 and 5. The gas discharge end of each elliptical
cross section tube section 88 projects through outer wall 30 at the
plenum 50 for discharging combustion gasses into the plenum under the
inducement of the inducer blower or fan 51 for discharge through the
discharge flue pipe 56. The side-by-side, spaced apart configuration of
the combustion gas heat exchanger tubes 70 is also shown in FIG. 4.

[0019]Referring again to FIG. 1 and also FIG. 5, the heater or furnace 10
includes a motor driven blower disposed within the housing 28 and
characterized by a drive motor 92 mounted on circumferentially spaced
brackets 94 which are connected to housing 28 in a conventional manner.
Motor 92 extends at least partially within opening 38 and is drivably
connected to a generally cylindrical, so-called squirrel cage type
centrifugal impeller 96 of conventional construction and disposed within
a portion of the interior space 71 of the housing 28 and substantially
surrounded by the heat exchanger tubes 70, as shown by way of example in
FIG. 5. Impeller 96 is disposed for rotation about axis 39. Another
advantageous aspect of the invention is provided by the orientation of
the tubes 70 which extend in a direction substantially within and
parallel to the plane of rotation of impeller 96 for maximizing exposure
to air flow exiting the outer circumference 96a of the impeller 96 and
across the width thereof. Accordingly, the heat exchanger of the furnace
10, comprising the plural spaced apart heat exchanger tubes 70, is
substantially integrated with the blower housing 28, and is exposed to
air entering the interior space 71 of the housing 28 as induced by the
blower or fan impeller 96 operating otherwise in a conventional manner.
Moreover, by providing plural spaced apart heat exchanger tubes for
conducting combustion gasses mixed with an induced and heated flow of air
from each of the burner nozzles 60, an efficient and high rate of heat
exchange may be accomplished in a relatively small space and without
degrading the performance of the motor driven blower or fan 96. Still
further, the configuration of the heat exchanger tubes 70 is such that,
as provided by the alternating straight and curved tube sections 74, 76,
78, 80, 81, 82, 83 and 84, for example, air being discharged from the
impeller 96 may flow over more than one section of a tube 70 as the flow
progresses in a counterclockwise direction, viewing FIG. 5, toward
opening 40, again to improve heat transfer. This improved heat transfer
results, at least in part, due to the proximity of straight tube sections
74, 78, 81 and 83 to the impeller 96 and the proximity of curved tube
sections 76, 80, 82 and 84 to the outer wall 30.

[0020]The construction and operation of the heater or furnace 10 is
believed to be within the purview of one skilled in the art based on the
foregoing description. Conventional engineering materials used for
furnace components, including blowers and heat exchangers and known to
those skilled in the art, may be used to construct the furnace 10.

[0021]Although a preferred embodiment of the invention has been described
in detail herein, those skilled in the art will recognize that various
substitutions and modifications may be made without departing from the
scope and spirit of the appended claims.